I think of this tool as like a barrier or something c':
It's to either prevent users from going through objects if they don't wish to , stand on certain things, etc.
Some objects however, won't really work with the collision no matter what you do I believe..
But all and all, that's pretty much what it is. Like a little barrier or wall to stop users from going through objects on a map and such. If there's gaps however like on the rock objects, then the user will still go through because nothing was preventing them from it.
Hope this cleared up some confusion, I'm sure there's an easier way. Lol.